烂尾船劫中劫

烂尾船低于市场价近50%的诱惑,使抄底烂尾船成为市场追逐的热点。三十年河东,三十年河西。伴随市场的跌宕起伏,船东、船企间不断进行着角色转换。危机阴影下的订单荒让往日风光无限的船厂无法保持淡定,不时爆出的烂尾船事件更是让船企如临深渊。那么,哪些＂烂尾船＂会成为船东抄底的抢手货？又是谁在追逐烂尾船的身影呢？金龟变烂尾的无奈2012年,随着订单快速萎缩和产能过快释放之间的矛盾日益深化,船厂正面临着＂订单接不来,船交不出去＂的双重阻击.     

Forging penetration efficiency of steel H13 stepped shaft radial forging with GFM forging machine

The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM (Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finite element code DEFORM 3D. According to the effective plastic strain, the mean stress and the mean plastic strain distribution of the radial forging, the forging penetration efficiency (FPE) was studied throughout each operation. The results show that the effective plastic strain in the center of the forging is always greater than zero for the desirable larger axial drawing velocity. The mean stress in the center of the workpiece is proposed to describe hydrostatic pressure in this paper. There is compressive strain layer beneath the surface of the workpiece to be found, while there is tensile strain core in the center of the workpiece. These results could be a valuable reference for designing the similar forging operations.     

中国海上执法力量变迁记

每次海上执法力量的发展变迁,都是国人海洋意识的进一步提升。日前,随着国家重新组建国家海洋局,以及国家海洋局将以中国海警局名义开展海上维权执法消息的披露,位于北京市复兴门的国家海洋局大门西侧的中国海监总队的牌子,不久将被换成中国海警局。触摸厚重的中国海上执法的历史年轮,海洋留下的记忆,都深深镌刻在每一个关心中国海洋事业的人的心里。从空白到璀璨,每次海上执法力量的发展变迁,都是国人海洋意识的进一步提升。     

寒冬中的深谋远虑

世界最大的集装箱航运巨头马士基是在押注,赌中国将在10年内从出口拉动型经济向消费型经济转变。2012年悲剧般的数据,让航运企业不得不面对不同结构海运市场下更加复杂严峻的战略选择。大浪淘沙智者胜,它不但考验着一个企业的生存智慧,更考验着整个行业如何在运筹帷幄中决胜于未来。     

代理模型技术及其在船舶板架强度和稳定性计算中的应用

对比分析了Kriging、径向基函数、多项式响应面三种代理模型在不同样本点比例和不同样本点空间分布下对4类典型数学函数的拟合精度和推广能力。研究结果表明,Kriging模型对典型数学函数具有较好的适用性和推广能力,径向基函数次之,多项式响应面的适应能力不足。在此基础上,基于Kriging方法构造了船舶双层底板架强度和稳定性计算代理模型,讨论了低样本点比例下Kriging模型代替有限元计算分析的适用性以及不同样本点空间分布对代理模型近似误差的影响。计算结果表明,在低样本点比例下一个均匀齐整的样本点空间分布更利于保证代理模型的精度。在所选取的样本点比例下Kriging模型对船舶板架强度和稳定性计算的适用性较好,近似误差满足工程精度要求。     

雷达抗干扰技术现状及发展趋势

介绍了国内外雷达抗干扰技术的发展现状,并从时域、频域、空域、极化域、信号处理以及抗干扰电路等方面介绍了目前国内研究的雷达抗干扰技术;分析了雷达抗干扰技术的发展趋势,以及新体制雷达的开发与抗干扰技术发展的关系.     

中国新一代大地基准—2000国家大地坐标系

采用地心坐标系作为大地基准是国际测量界的总趋势.论文详细介绍了2008年7月1日启用的中国三维地心坐标系CGCS2000的定义及其实现,给出了采用参考椭球的定义常数和导出常数,将CGCS2000与WGS84进行了比较,分析了椭球扁率变化引起的同一点在两种坐标系下大地坐标和两种椭球面上正常重力、正常重力垂直梯度的差异.     

两种低碳铬钼钢的等温淬火组织和性能

研究了低碳铬钼钢ZG25MnCrNiMo钢和25CrMo4钢在不同温度下等温淬火的组织与性能.分别用金相显微镜、扫描电子显微镜观察了钢的微观组织和冲击断口形貌.结果表明,两种低碳铬钼钢在较低的等温温度下得到均匀的下贝氏体组织,此时抗拉强度和冲击功均达到最大值;等温温度升高,组织变得粗大,性能下降,形成粒状贝氏体组织.ZG25MnCrNiMo钢等温转变形成贝氏体后综合性能下降,而25CrMo4钢等温转变形成贝氏体后宏观表现为强度高韧性差.     

三维矩形弹性液舱内液体晃荡数值模拟研究

为了解三维弹性液舱内液体晃荡情况,采用ADINA模拟不同激励频率下液舱内液体的晃荡,将所得的结果与解析解进行对比,得到不同载液率下弹性液舱内液体晃荡特点,得到液舱载液率、外界激励等参数变化对液体自由表面运动及晃荡荷载的影响.     

海底犁式挖沟机犁体曲面优化设计(英文)

The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the towing force of a vessel. A multi-objective genetic algorithm based on analytical models of the plow surface has been examined and applied in efforts to obtain optimal design of the plow. For a specific soil condition, the draft force and moldboard surface area which are the key parameters in the working process of the plow are optimized by finding the corresponding optimal values of the plow blade penetration angle and two surface angles of the main cutting blade of the plow. Parameters such as the moldboard side angle of deviation, moldboard lift angle, angular variation of the tangent line, and the spanning length are also analyzed with respect to the force of the moldboard surface along soil flow direction. Results show that the optimized plow has an improved plow performance. The draft forces of the main cutting blade and the moldboard are 10.6% and 7%, respectively, less than the original design. The standard deviation of Gaussian curvature of moldboard is lowered by 64.5%, which implies that the smoothness of the optimized moldboard surface is much greater than the original.